rcu: Make rcu_gp_cleanup() write only once to ->gp_flags

At the end of rcu_gp_cleanup(), if another grace period is needed, but
not via rcu_accelerate_cbs(), the ->gp_flags field is written twice,
once when making the new grace-period request, and once when clearing
all other types of requests.  This commit therefore adds an else-clause
to avoid this double write.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 6ce82c009195..a9a4a260ea7d 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2117,8 +2117,9 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
                 rsp->gp_req_activity = jiffies;
                 trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum),
                                        TPS("newreq"));
+        } else {
+                WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
         }
-        WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
         raw_spin_unlock_irq_rcu_node(rnp);
 }